[dalias]

LD_PRELOAD alone wouldn't do it because glibc's dynamic linker is closely tied to glibc. In particular thread-local storage requires close cooperation between them. Likewise, musl needs its own dynamic linker.

What could be done in theory is replacing /lib/ld-linux.so.2 with a symlink to musl. One of the long-term goals for musl is for this to actually work, at least for many programs. But right now there are a lot of glibc-specific symbols that get pulled in magically by glibc's headers, even when the program at the source-level is 100% portable code, and we don't have coverage for all of these.

[throwawayaway]

Excellent response! I have a program that spends 10% of it's time in vfprintf for string processing, and I really think the program should not be spending that much time/any time there. I looked at the libc6 vfprintf implementation and it's pretty esoteric looking stuff. It might be worth my time using your library or something similar to swap it out.

[justincormack]

Musl has the benefit of being very readable, and you can just use bits of code if you like due to the license.